<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <div v-bind:class="{box}">我是box
            <div v-bind:class="{inner}">我是inner1</div>
            <div v-bind:class="{inner}">我是inner2</div>
        </div>
        
    </div>
    <script>
        var vm = new Vue({
            el:"#app",
            data:{
                box:'box',
                inner :'inner'
            }
        })
    </script>
    
</body>
</html>